Image sensor and method of fabricating same

Abstract

An image sensor includes; a substrate having a first surface and an opposing second surface and including unit pixels respectively having photoelectric conversion regions, a semiconductor pattern disposed in a first trench defining the unit pixels, the semiconductor pattern including a first semiconductor layer provided on an inner surface of the first trench and a second semiconductor layer provided on the first semiconductor layer, and a first contact provided on the second surface and connected to the semiconductor pattern. A height of the first semiconductor layer from a bottom surface of the first trench is less than a height of the second semiconductor layer from the bottom surface of the first trench.

The invention claimed is: 
     
       1. An image sensor, comprising:
 a substrate comprising a first surface and a second surface opposing to the first surface; 
 a first pixel region in the substrate; 
 a second pixel region in the substrate; 
 an isolation trench disposed between the first pixel region and the second pixel region, wherein the isolation trench penetrates the substrate; 
 a capping layer disposed in the isolation trench and in contact with the first surface; and 
 a pattern in the isolation trench and in contact with the capping layer; 
 wherein the pattern includes a second layer in the isolation trench and a first layer disposed between the second layer and an inner surface of the isolation trench, 
 wherein the first and second layers are in contact with the second surface and are spaced vertically apart from the first surface, 
 wherein a distance from a first surface of the capping layer to the first surface of the substrate is less than a distance from the second surface of the substrate to a first surface of the second layer, 
 wherein the capping layer is vertically overlapping with the pattern, 
 wherein the first surface of the capping layer is spaced apart from the first surface of the substrate, 
 wherein the first surface of the second layer is spaced apart from the first surface of the substrate, 
 wherein the capping layer includes a first material, and wherein the first layer includes a second material different from the first material, 
 wherein the image sensor is configured to receive light from the second surface of the substrate, and 
 wherein the first layer has a first side surface and a second side surface opposing the first side surface along a lateral direction, and 
 wherein the second side surface of the first layer has a first curved shape that curves from an inside of the isolation trench toward the inner surface of the isolation trench near the first surface of the capping layer. 
 
     
     
       2. The image sensor of  claim 1 , wherein the second layer has a second surface that has the first curved shape and is in contact with the second side surface of the first layer along the lateral direction. 
     
     
       3. The image sensor of  claim 2 , wherein the second surface of the second layer is spaced apart from the first surface of the capping layer. 
     
     
       4. The image sensor of  claim 3 , wherein the second layer includes the second material. 
     
     
       5. The image sensor of  claim 3 , wherein the first material is silicon oxide. 
     
     
       6. The imager sensor of  claim 3 , wherein the isolation trench has a first width at the first surface of the substrate in a first direction and the isolation trench has a second width at the second surface of the substrate in the first direction,
 wherein the first width is greater than the second width, and 
 wherein the first direction is parallel to the first surface of the substrate. 
 
     
     
       7. The image sensor of  claim 6 , wherein the second layer has a third width in the first direction at a first vertical point,
 wherein the first vertical point is disposed between the first surface of the second layer and the second surface of the substrate, and 
 wherein the third width is between 10 nm and 200 nm. 
 
     
     
       8. The image sensor of  claim 7 , wherein the first layer has a fourth width in the first direction at the first vertical point,
 wherein the fourth width is from the first side surface of the first layer to the second side surface of the first layer and 
 wherein the third width is greater than the fourth width. 
 
     
     
       9. The image sensor of  claim 8 , wherein a distance from the first surface of the second layer to the second surface of the substrate in a vertical direction is about 3 μm to about 8 μm. 
     
     
       10. An image sensor, comprising:
 a substrate comprising a first surface and a second surface opposing to the first surface; 
 a first pixel region in the substrate; 
 a second pixel region in the substrate; 
 an isolation trench disposed between the first pixel region and the second pixel region, wherein the isolation trench penetrates the substrate; 
 a capping layer disposed in the isolation trench and in contact with the first surface; and 
 a pattern in the isolation trench and in contact with the capping layer; 
 wherein the pattern includes a second layer and a first layer disposed between the second layer and an inner surface of the isolation trench, 
 wherein the first layer has a first surface in contact with the second surface of the substrate and a second surface opposing the first surface of the first layer along a vertical direction, 
 wherein a distance from a first surface of the second layer to the first surface of the substrate is different from a distance from the second surface of the first layer to the first surface of the substrate, 
 wherein the capping layer includes a first material, and wherein the first layer includes a second material different from the first material, 
 wherein the capping layer is vertically overlapping with the pattern, 
 wherein the first surface of the second layer is spaced vertically apart from the first surface of the substrate and the second surface of the first layer is spaced vertically apart from the first surface of the substrate, 
 wherein the image sensor is configured to receive light from the second surface of the substrate, and 
 wherein a distance from a first surface of the capping layer to the first surface of the substrate is less than a distance from the second surface of the substrate to the first surface of the second layer, and 
 wherein the first surface of the capping layer is spaced vertically apart from the first surface of the substrate. 
 
     
     
       11. The image sensor of  claim 10 , wherein the distance from the first surface of the capping layer to the first surface of the substrate is different from the distance from the second surface of the first layer to the first surface of the substrate. 
     
     
       12. The image sensor of  claim 11 , wherein the capping layer includes silicon oxide. 
     
     
       13. The image sensor of  claim 11 , wherein the first layer has a first side surface and a second side surface opposing the first side surface along a lateral direction, and
 wherein the second side surface of the first layer has a first curved shape that curves from an inside of the isolation trench toward the inner surface of the isolation trench near the first surface of the capping layer. 
 
     
     
       14. The image sensor of  claim 13 , wherein the second layer has a second surface that has the first curved shape and is in contact with the second side surface of the first layer along the lateral direction. 
     
     
       15. The image sensor of  claim 13 , wherein the first layer has a first width in a first direction at a first vertical point,
 wherein the second layer has a second width in the first direction at the first vertical point, 
 wherein the first vertical point is disposed between the first surface of the second layer and the second surface of the substrate, and 
 wherein the first direction is parallel to the first surface of the substrate. 
 
     
     
       16. The image sensor of  claim 15 ,
 wherein the first width is between 3 nm and 35 nm. 
 
     
     
       17. The image sensor of  claim 16 ,
 wherein the second width is greater than the first width. 
 
     
     
       18. An image sensor, comprising:
 a substrate comprising a first surface and a second surface opposing to the first surface; 
 a first pixel region in the substrate; 
 a second pixel region in the substrate; 
 an isolation trench disposed between the first pixel region and the second pixel region, wherein the isolation trench penetrates the substrate; 
 a capping layer disposed in the isolation trench and in contact with the first surface; and 
 a pattern in the isolation trench and in contact the capping layer; 
 wherein the pattern includes a second layer in the isolation trench and a first layer disposed between the second layer and an inner surface of the isolation trench, 
 wherein the first and second layers are in contact with the second surface and are spaced apart from the first surface, 
 wherein a distance from a first surface of the capping layer to the first surface of the substrate is less than a distance from the second surface of the substrate to a first surface of the second layer, 
 wherein the first layer has a first surface in contact with the second surface of the substrate and a second surface opposing the first surface of the first layer along a vertical direction, 
 wherein the distance from the first surface of the capping layer to the first surface of the substrate is different from a distance from the second surface of the first layer to the first surface of the substrate, 
 wherein the capping layer is vertically overlapping with the pattern, 
 wherein the first surface of the capping layer is spaced apart from the first surface of the substrate, 
 wherein the first surface of the second layer is spaced apart from the first surface of the substrate, 
 wherein the capping layer includes a first material, and wherein the first layer includes a second material different from the first material, 
 wherein the image sensor is configured to receive light from the second surface of the substrate, and 
 wherein the first layer has a first side surface and a second side surface opposing the first side surface along a lateral direction, and 
 wherein the second side surface of the first layer has a first curved shape that curves from an inside of the isolation trench toward the inner surface of the isolation trench near the first surface of the capping layer. 
 
     
     
       19. The image sensor of  claim 18 , wherein the second layer has a second surface that has the first curved shape and is in contact with the second side surface of the first layer along the lateral direction. 
     
     
       20. The image sensor of  claim 19 , wherein the isolation trench has a first width at the first surface of the substrate in a first direction and the isolation trench has a second width at the second surface of the substrate in the first direction,
 wherein the first width is greater than the second width, and 
 wherein the first direction is parallel to the first surface of the substrate.